JPH06287943A - Foot protection method for tip of foundation pile and cylindrical foundation pile - Google Patents

Abstract

PURPOSE:To apply the method even for execution of a foundation pile of small diameter, and provide large supporting force and resisting force against drawing out. CONSTITUTION:A cylindrical foundation pile main body 1 is mounted to a rotation device 12, and the pile main body 1 is press-fitted up to prescribed depth (a) while normally rotating. At this time, if necessary, air is jetted from the nozzle of a force feed pipe 5 inserted in the pile main body 1, so as to reduce wall friction between the inner wall of the pile main body 1 and inner earth and sand. At reaching the prescribed depth (a), the pile main body 1 is reversely rotated so as to open spread blades 3 and perform spread drilling. Foot protective material 14 is Jetted through the force feed pipe 5. By hardening of the foot protective material 14 stirred and mixed with earth and sand by means of the spread blades 3, a spread foot protection part 15 in which the spread blades 3 in the opened condition is used both as an anchor and reinforcing material, is completed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tip root consolidation method for imparting a sufficient vertical support force and pullout resistance force to the root consolidation portion at the tip of a tubular foundation pile such as a steel pipe pile, and a tubular shape used for the method. It relates to foundation piles.

[0002]

2. Description of the Related Art As a method of burying pre-formed piles such as steel pipe piles in the ground without vibration and noise, an auger is inserted into a tubular foundation pile and a hole for burying the pile is drilled in the ground with an auger. At the same time, there are a hollow excavation method in which a foundation pile is press-fitted, a burial construction method in which a hole for burying a pile is excavated in advance on the ground by an auger, and then the foundation pile is press-fitted into the hole.

By the way, in addition to the self-weight of the structure, a pushing force and a pulling force act on the foundation piles supporting the civil engineering and building structures in addition to the self-weight of the structure. The frictional force between the outer surface of the foundation pile and the ground contributes to the pull-out force as a resistance force, but a large resistance force cannot be expected in many cases.

Therefore, in order to cope with the pushing force and the pulling force, the number of foundation piles is increased to reduce the pushing force and the pulling force per pile, and the pile diameter is increased to reduce the peripheral frictional force. The design will be reviewed by methods such as increasing it, but this will lead to an increase in material costs and construction costs. Therefore, it is desired to improve the push-in / pull-out resistance of each pile, that is, to develop a foundation pile having a large push-in / pull-out resistance.

Conventionally, the tip portion of the foundation pile constructed by the medium excavation and consolidation method is excavated by enlarging the diameter of the pile, and the cement excavating material such as cement milk and mortar is poured into the enlarged excavated portion and stirred. In some cases, the pressure receiving area at the tip of the pile is increased and the allowable pushing force is improved by solidifying and solidifying. However, the adhesive force between the tip of the pile and the rooting material of the enlarged excavating part is usually insufficient, so that it does not function very well against the pulling force.

On the other hand, in Japanese Examined Patent Publication No. 1-25848, a plurality of ring-shaped projections are attached to the inner and outer surfaces of the tip of the tubular foundation pile to increase the adhesive force with the rooting material.
It is described that the support force is increased. Further, in Japanese Patent Laid-Open No. 62-29614, an anchor member such as a reinforcing bar is fixed to the lower end of a tubular foundation pile, and the foundation pile and the rooting material are integrated through the anchor member. Is listed.

Incidentally, the conventional expansion excavation is generally performed by a ground excavation member such as an expansion blade provided on an auger head capable of expanding the diameter. Some expansion wings have a locking mechanism that prevents the expansion wings from opening more than a certain angle, and automatically open and close by using the ground reaction force when the auger rotates forward and backward. , When the auger is rotated forward, it is in a contracted state due to the reaction force from the ground to the inside of the auger axial direction, and when it is rotated in the reverse direction, it is expanded due to the reaction force from the ground to the outside in the axial direction of the auger. The enlarged state opened by a predetermined angle is maintained.

[0008]

[Problems to be Solved by the Invention] Japanese Patent Publication 1-2
Both the pile described in Japanese Patent No. 5848 and the root-setting method described in Japanese Patent Laid-Open No. 62-29614 aim to increase the adhesive force with the root-hardening material, but are described in Japanese Patent Publication No. 1-25848. In order to obtain pull-out resistance with a thing, it is necessary to make the tip of the foundation pile with the projection sufficiently pushed into the rooting material.

In the case of the root consolidation method described in Japanese Patent Laid-Open No. 62-29614, it is sufficient that the anchor member is pushed into the root anchor material, but when the pile is sunk or press-fitted while the anchor member is fixed, There is a high possibility that the anchor member may bend due to contact with earth and sand or contact with blades of an excavator such as an earth auger. In addition, it is inconvenient to handle and transport the pile with the anchor member protruding, and even when the pile is built, the construction efficiency is lowered for the same reason.

Further, in the conventional hollow excavation method, since the auger is inserted into the inside of the pile main body, the tubular foundation pile is
Only those with an inner diameter greater than the outer diameter of the auger can be constructed, and therefore it cannot be applied to the construction of small-diameter foundation piles.

The present invention provides a method for consolidating the tip of a foundation pile that can be applied to the construction of a small-diameter foundation pile and can obtain a large supporting force and pullout resistance, and a tubular foundation pile used in the method. The purpose is to do.

[0012]

In the foundation pile consolidation method of the foundation pile of the present invention, instead of using the conventional auger of the medium excavation method, a ground excavating member capable of expanding the diameter at the pile body tip portion of the tubular foundation pile. Is installed, and the pile body is pressed into the ground while rotating itself.

When the tubular foundation pile reaches a predetermined depth in the ground, the diameter of the ground excavation member is expanded to carry out expanded excavation. On the other hand, insert a press-fitting pipe inside the pile main body of the tubular foundation pile,
A rooting material such as cement milk is injected into the expanded excavated portion through the press-fitting pipe and mixed with the excavated soil to form the expanded rooted portion.

The ground excavation member functions as an anchor for the expanded soil consolidation portion of the foundation pile and a reinforcement material for the expanded soil consolidation portion by hardening the soil consolidation material while the diameter of the soil excavation member is expanded.

The tubular foundation pile of the present invention is for use in the above-mentioned construction method, and is a tubular pile main body provided with a ground excavating member capable of expanding its diameter at the tip thereof.

For expanding the diameter of the ground excavation member, the same mechanism as in the case of the conventional auger for expansion excavation can be used,
The pile body of the foundation pile has the function of an auger shaft.

Also in the present invention, it is possible to use, as the ground excavating member, the expanding blade of the type which is automatically opened and closed by utilizing the reaction force of the ground used in the auger as described in the section of the prior art. In that case, a structure in which a cylindrical excavation shaft is attached to the tip of the pile body and a plurality of expanding blades are provided on the outer peripheral surface thereof is conceivable. Alternatively, the enlarged wings may be provided directly on the pile body. Of course, the method of expanding the diameter is not limited to this, and a method of expanding the diameter by performing a necessary operation may be used.

Further, in the present invention, since the cylindrical foundation pile itself is rotated by the rotating device for excavation and press-fitting, an excavation bid or a stirring blade, etc. may be provided at the tip of the pile body or the tip of the excavation shaft portion as required. , A blade member for drilling is provided.

Further, it is necessary to eject the rooting material for forming the expanded rooting portion from the tip of the pile. As a mechanism for this, a pressure feed pipe in which the pile body or the excavating shaft portion is inserted into the pile body is used. It is conceivable to provide a guide portion for guiding and supporting the tip of the.

The tubular foundation pile in the present invention includes a hollow concrete pile, a hollow steel-concrete composite pile, etc. in addition to the steel pipe pile.

[0021]

1 (a) to 1 (c) show a construction procedure in an embodiment of the present invention, and FIGS. 2 (a) to 2 (c) show a main part of a cylindrical foundation pile and its A 3A and 3B show a cross section A-A and a cross section B-B, respectively.

First, the main structure of the tubular foundation pile in this embodiment will be described with reference to FIGS. 2 (a) to 2 (c).

In this embodiment, a bottom plate 2 is provided at the tip of a pile body 1 made of steel pipe or the like, and a cylindrical excavating shaft portion 6 is integrally attached to the lower surface of the bottom plate 2.

At the tip of the excavation shaft portion 6, a blade member 9 in the shape of a stirring blade for drilling is attached. Further, the blade member 9
The guide body 10 is provided in the center of the horizontal cross section of the pile body 1 so as to fit into the notch of the blade member 9.
Also, the tip of the pressure-feeding pipe 5 inserted into the excavation shaft portion 6 is guided in the vertical direction, and the tip of the pressure-feeding pipe 5 is prevented from swinging.

In the figure, reference numeral 11 denotes an ejection hole formed at the tip of the pressure-feeding pipe 5, and a rooting material is injected into the ground through the ejection hole 11. It should be noted that at a predetermined depth, air can be sent to the pressure feed pipe 5 and jetted from the jet hole 11 as necessary.

On the outer peripheral surface of the excavating shaft portion 6, a plurality of expanding blades 3 are provided as a ground excavating member whose diameter can be expanded. The base of the expansion wing 3 is attached to a pin 8 having a pair of fixed plates 7 protruding from the outer surface of the excavation shaft 6 as bearings.
It can be opened and closed around the pin 8. When the expansion wings 3 open due to the reverse rotation of the pile body 1, the base end of the expansion wings 3 hits the outer surface of the excavation shaft 6 as shown in Fig. 2 (b), and the expansion wings 3 do not open more than necessary. Locks.

Further, in this embodiment, round steel 4 is spirally attached to the tip outer peripheral surface of the pile body 1. This is to improve the adhesive force in the enlarged root consolidation portion 15,
It is a protrusion that is attached as necessary and is not limited to the round steel 4 and may be a block or plate. The spiral shape is used to reduce resistance when the pile main body 1 is rotationally press-fitted.

Next, this embodiment will be described along with the construction procedure with reference to FIGS.

First, the pile body 1 is attached to the rotating device 12,
While the pile body 1 is rotated in the forward direction, it is press-fitted to a predetermined depth. In Fig. 1 (a), a is a rooting material 14 such as cement milk.
Refers to the depth at which the spout begins.

Until the depth a is reached, air is pressure-fed by a pressure-feeding pipe 5 inserted into the pile body 1 as necessary, and the air ejected from the ejection holes 11 causes a wall surface between the inner wall of the pile body 1 and the earth and sand inside. Friction can be reduced and the required rotation output of the rotation device 12 can be reduced.

After reaching the depth a, the pile body 1 is reversely rotated as shown in FIG. continue,
The pressure feed pipe 5 is pushed down until the tip projects below the blade tip member 9 and the guide 10, and the ejection hole 1 at the tip of the pressure feed pipe 5 is pushed down.
The rooting material 14 is spouted from 1.

In this work step, the root consolidation portion is enlarged, and the root consolidation material 14 and the earth and sand are stirred and mixed.
5 begins to form.

In FIG. 1 (c), the foundation portion is sufficiently formed up to a predetermined depth b, and the reverse rotation of the pile body 1 and the foundation material 1 are performed.
4 shows a state in which pressure feeding and jetting of No. 4 are about to be stopped.

Although not shown, after the work steps shown in FIG. 1 (c) are completed, the pressure feeding pipe 5 is pulled out and pulled out. Further, the rotating device 12 is also removed from the pile body 1.

By the above-mentioned work, the enlarged root consolidation portion 15 is formed to a predetermined depth. At this time, the enlarged blade 3 can be kept open in the enlarged root consolidation portion 15.

Since the expansion wings 3 are fixed in the open state, the expansion wings 3 serve as anchors to the expansion consolidation portion 15, and the pile body 1 and the expansion consolidation portion 15 are more firmly integrated. The foundation pile can be pushed in and the pull-out strength can be improved.

Further, since the enlarged root consolidation portion 15 having a diameter larger than the outer diameter of the pile main body 1 is formed, the upper surface of the enlarged root consolidation portion 15 is against the pulling force acting on the pile main body 1. It is expected that the pull-out resistance will increase in response to the reaction force from.

With respect to the pushing force acting on the pile main body 1, since the bottom area of the enlarged root consolidation portion 15 is wide, the effect of reducing the sharing pressure per unit area is
It becomes possible to endure a larger pushing force.

[0039]

Advantageous Effects of Invention Having a ground excavation member capable of expanding the diameter in a tubular foundation pile itself,
Since it does not require an auger for the medium excavation method, it can also be applied to the construction of small-diameter foundation piles.

By fixing the diameter of the ground excavation member in the expanded root consolidation part, the ground excavation member functions as an anchor and a reinforcing material for the expanded root consolidation part, and not only the supporting force against the pushing force but also the high pulling out force. It is possible to exert proof stress.

By increasing the push-in / pull-out resistance per pile, the pile diameter can be reduced or the number of piles can be reduced.

Construction cost can be reduced by reducing the number of piles, reducing the diameter of piles, and simplifying construction equipment.

[Brief description of drawings]

1A to 1C are vertical sectional views showing a construction procedure in an embodiment of a construction method of the present invention.

FIG. 2 shows an embodiment of the tubular foundation pile of the present invention, where (a) is a front view of an essential part (the upper part is a vertical sectional view), (b) is its AA sectional view, c) is a BB sectional view.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Pile main body, 2 ... Bottom plate, 3 ... Expansion blade, 4 ... Round steel, 5 ... Pumping pipe, 6 ... Excavation shaft part, 7 ... Fixed plate, 8 ... Pin, 9 ...
Blade member, 10 ... Guide, 11 ... Spout hole, 12 ... Rotating device, 13 ... Ground, 14 ... Rooting material, 15 ... Expanded rooting portion,

Claims (4)

[Claims] 1. A ground excavation member capable of expanding a diameter is provided at a tip end of a pile main body of a tubular foundation pile, and the pile main body itself is pressed into the ground while rotating, and the ground excavation is performed when a predetermined depth is reached. In addition to expanding the diameter of the member and expanding the excavation, a rooting material is injected into the expanded excavating portion from the press-fitting pipe inserted through the inside of the pile main body to form an expanded rooting portion, and the ground is located in the expanded rooting portion. A method of consolidation of the foundation piles, characterized in that the excavated member is fixed in the expanded state. 2. A tubular foundation pile, characterized in that a ground excavation member capable of expanding the diameter is provided at the tip of the tubular pile body. 3. The tubular foundation pile according to claim 2, wherein the ground excavating member is a plurality of expanding blades attached to an outer peripheral surface of an excavating shaft portion attached to a tip end portion of the pile body. 4. A cutting edge member for drilling and a guide portion for guiding and supporting a tip of a pressure-feeding pipe for injecting a rooting material inserted into a tubular pile body are provided at a tip of the excavating shaft portion. The tubular foundation pile according to claim 3.